Method of using cis-urocaninic acid for topically treating psoriasis

ABSTRACT

Dermatological compositions having an effective content of cis-urocaninic acid and/or its derivatives, the process for the produktion of such compositions and the method of use of dermatological compositions having a content of cis-urocaninic acid for the treatment and the prophylaxis of inflammatory dermatoses and for the care and restoration of senstive and stressed skin.

This application is a continuation of application Ser. No. 08/007,448,filed Jan. 22, 1993, now abandoned, which is a continuation in part ofSer. No. 07/722,062, filed on Jun. 27, 1991, now abandoned.

The present invention relates to products for the treatment andespecially for the prophylaxis of inflammatory or allergic dermatosesand for the care and restoration of sensitive or stressed skin. Thepresent invention further relates to preparations for topicalapplication.

Dermatoses produce a great burden of suffering on the affected. Thenumber of inflammatory or allergic dermatoses is continuously increasingin the industrialized countries. Investigations confirm thatoccupationally related skin disorders obviously play a substantial rolehere. Occupational dermatoses are especially of existential importancefor the affected persons, since in many cases they force a change ofoccupation. At the least, however, they require increased precautionarymeasures.

Most common widespread are metal allergies, particularly allergies toheavy metals, such as nickel, copper and chromium.

Since, in many states of the world, many coins essentially consist ofnickel alloys, avoiding the contact to nickel proves nearly impossible.Prophylaxis, healing or at least relief of nickel allergy is, therefore,an important aim of the present invention.

Products for the treatment of these disorders are known per se, andantihistaminics or glucocorticoids are employed in particular. Forprophylaxis, on the other hand, no suitable preparations are hithertoknown.

However, the compositions of prior art, which in the meantime areemployed in many commercial forms, have some disadvantages: in manypeople, antihistaminics cause languor and drowsiness. Permanent use ofglucocorticoids (for example cortisone) is usually unjustifiable formedical reasons owing to many unpleasant side effects. The same alsoapplies to most so-called NSAID (non-steroidal anti-inflammatory drugs).

It was thus the object of the present invention to find ways to avoidthe disadvantages of the prior art. In particular, it was intended tomake agents available which can be employed effectively for thetreatment and prophylaxis of inflammatory or allergic dermatoses and forthe care and restoration of sensitive or stressed skin without the sideeffects described occuring.

According to the invention these objects are achieved by dermatologicalcompositions for the treatment or prophylaxis of psoriasis, allergies,particularly allergies to heavy metals, neurodermatitis (neurodermitis)and for the care and restoration of sensitive or stressed skin, saidcompositions having an effective content of cis-urocaninic acid and/orits dermatologically or pharmaceutically acceptable salts.

cis-Urocaninic acid (also known as cis-urocanic acid orcis-4-imidazolylacrylic acid) is characterized by the followingstructural formula: ##STR1##

It has the molecular formula C₆ H₆ N₂ O₂ and the molecular weight138,12. cis-Urocaninic acid is formed, for example by UV irradiation ofthe trans-isomer, which occurs in human skin and also in perspiration.The use of the trans-isomer as a sunscreen is known.

It has been shown in the most highly surprising way that cis-urocaninicacid has an anti-inflammatory action, alleviates the consequences ofallergic reactions and to a great extent prevents allergic reactions.

Because of these anti-inflammatory and anti-allergic power thecompositions according to the invention are active against psoriasis,neurodermitis and contact dermatitis.

It is supposed that at least some of the advantageous effects ofurocaninic acid can be interpreted as being due to sequestering of smallmolecules or ions by urocanic acid. It has been proved by experimentsthat metal ions, in particular heavy metal ions such as Ni²⁺, Cr³⁺,Co²⁺, Co³⁺ and Cu²⁺, are sequestered by cis-urocaninic acid in form ofcomplexes.

Nocuous small molecules or ions being sequestered by cis-urocaninic acidin dermatological formulations is thus another feature of the presentinvention.

In the compositions according to the invention the cis-urocaninic acidis preferably present in concentrations of 0.00001 mg/ml-60 mg/ml.Preferred are compositions having concentrations of 0.01 mg/ml-2.0mg/ml, especially those of 0.05 mg/ml-1.0 mg/ml.

The compositions according to the present invention are appliedtopically, on the skin of the patient. Preferred are severalapplications a day over a period and in quantities sufficient to givealleviation to the affected person, for example 14 days.

The compositions according to the present invention are equally appliedtopically, on the skin of the patient, if prophylaxis is intended.Preferred are several applications a day over a period and in sufficientquantities to the patient, for example 14 days.

cis-Urocaninic acid-containing formulations according to the inventioncan advantageously be selected from all commercial forms, for examplecreams, gels, lotions, sprays, milks etc. It has proved favorable toincorporate aqueous or alcoholic/aqueous or alcoholic or acetone/aqueousor acetone or acetone/alcoholic solutions of cis-urocaninic acid in theformulations.

It is furthermore advantageous to embody diluents, auxiliaries and/oradditives in the compositions, which increase the stability ofcis-urocaninic acid or its derivatives or which improve or modify thequality of the compositions from the pharmaceutical viewpoint.

Auxiliaries and additives are, for example, thickeners, fillers,colorants, emulsifiers, additional active compounds such aslightscreens, stabilizers, antioxidants, preservatives, alcohol, water,salts, substances having proteolytic or keratolytic activity etc.

It is especially advantageous to add unsaturated fatty acids to thecompositions according to the invention, since these increase the effectof the cis-urocaninic acid further in a surprising way. Preferred acidshere are gamma-linolenic acid, eicosapentaenoic acid, docosahexaenoicacid, oleic acid and their derivatives, advantageously the correspondingesters and salts. The unsaturated acids or the corresponding derivativesare preferrably present in concentrations of 0.2-2.0% by weight, relatedto the entire weight of the composition.

It is perfectly convenient to use mixtures of cis- and trans-urocaninicacid. The effect according to the invention here indeed emanates fromthe cis-compound, but the user can make use of the properties, e.g.light-protecting properties, of the trans-compound as well.

In particular, it is also advantageous to expose trans-urocaninic acidto ultraviolet radiation, whereupon a mixture of cis- and trans-isomersis formed, and to incorporate this mixture into the appropriateformulation.

Otherwise, the customary measures which are known to the person skilledin the art are to be observed.

The following examples are used to describe the invention without itbeing intended to restrict the invention to these examples.cis-urocaninic acid is abbreviated in the examples as UCA.

EXAMPLE 1

Aqueous preparation (face lotion)

    ______________________________________                                                           % by weight                                                ______________________________________                                        PEG-40-hydrogenated Castor Oil                                                                     0.811                                                    Dipropylenglycol     2.534                                                    PEG-8                1.521                                                    Na.sub.3 EDTA        0.253                                                    Polymer JR 125       0.025                                                    UCA                  0.750                                                    Water demin.         to 100.000                                               ______________________________________                                    

EXAMPLE 2

Aqueous composition

    ______________________________________                                                             % by weight                                              ______________________________________                                        Polyfatty acid ester (Cetiol HE)                                                                     16.000                                                 PPG-3-myristyl ether (Witconol APM)                                                                  1.000                                                  Propylene glycol       3.000                                                  Glycerol               40.000                                                 UCA                    0.500                                                  Water demin.           to 100.000                                             ______________________________________                                    

EXAMPLE 3

Hydrogel (Polyacrylate gel)

    ______________________________________                                                              % by weight                                             ______________________________________                                        Acrylic acid polymer (Carbopol 934)                                                                   1.000                                                 Tris(hydroxymethylamino)methane (Tris)                                                                1.000                                                 Glycerol                2.000                                                 Propylene glycol        2.000                                                 UCA                     0.050                                                 Water demin.            to 100.000                                            ______________________________________                                    

EXAMPLE 4

Preparation having a high water content (very soft)

    ______________________________________                                                         % by weight                                                  ______________________________________                                        Ceteareth (Cremophor A 25)                                                                       0.100                                                      Cetearyl Alcohol (Lanette O)                                                                     0.400                                                      Petroleum jelly GP 9                                                                             12.500                                                     Mineral Oil GP 9   11.000                                                     Ceteareth-6-stearyl alcohol                                                                      6.000                                                      (Cremophor A6)                                                                UCA                0.020                                                      Water demin.       to 100.000                                                 ______________________________________                                    

EXAMPLE 5

Preparation having a high water content (soft)

    ______________________________________                                                          % by weight                                                 ______________________________________                                        Ceteareth-25 (Cremophor A25)                                                                      1.500                                                     Cetearyl Alcohol (Lanette O)                                                                      8.500                                                     UCA                 0.250                                                     Water demin.        to 100.000                                                ______________________________________                                    

EXAMPLE 6

Preparation having a high water content (soft)

    ______________________________________                                                          % by weight                                                 ______________________________________                                        Ceteareth-25 (Cremophor A25)                                                                      2.000                                                     Cetearyl alcohol (Lanette O)                                                                      8.000                                                     Petroleum jelly, GP 9                                                                             10.000                                                    Mineral Oil, GP 9   10.000                                                    UCA                 0.100                                                     Water demin.        to 100.000                                                ______________________________________                                    

EXAMPLE 7

Preparation having a high water content (semisolid)

    ______________________________________                                                         % by weight                                                  ______________________________________                                        Ceteareth-25       3.000                                                      Cetearyl Alcohol (Lanette O)                                                                     17.000                                                     UCA                0.175                                                      Water demin.       to 100.000                                                 ______________________________________                                    

EXAMPLE 8

Watery lotion

    ______________________________________                                                          % by weight                                                 ______________________________________                                        Ceteareth-25 (Cremophor A25)                                                                      1.000                                                     Ceteareth-6-stearyl alcohol                                                                       1.000                                                     (Cremophor A6)                                                                Glycerol-mono-distearate                                                                          2.000                                                     (Tegin normal)                                                                Cetyl alcohol       1.000                                                     Isopropyl myristate 1.450                                                     Glycerol            1.000                                                     Polyvinylpyrrolidone                                                                              0.500                                                     UCA                 0.125                                                     Water demin.        to 100.000                                                ______________________________________                                    

EXAMPLE 9

Viscous lotion

    ______________________________________                                                          % by weight                                                 ______________________________________                                        Ceteareth 25 (Cremophor A25)                                                                      2.000                                                     Cetearyl Alcohol (Lanette O)                                                                      3.000                                                     Mineral Oil, GP 9   5.000                                                     Propylene glycol    3.000                                                     Polyvinylpyrrolidone                                                                              0.500                                                     UCA                 0.300                                                     Water demin.        to 100.000                                                ______________________________________                                    

EXAMPLE 10

W/O-Cream

    ______________________________________                                                             % by weight                                              ______________________________________                                        Glycerol sorbitan fatty acid ester                                                                   6.000                                                  (Arlacel 481)                                                                 Mikrocrystalline Wax   1.000                                                  (Lunacera M)                                                                  Neutral Oil            3.000                                                  Paraffin Oil           19.000                                                 Magnesium stearate     1.000                                                  Propylene glycol       3.700                                                  Magnesium sulphate (MgSO.sub.4 * 7 H.sub.2 O)                                                        0.700                                                  UCA                    1.000                                                  Water demin.           to 100.000                                             ______________________________________                                    

EXAMPLE 11

W/O-Emulsion

    ______________________________________                                                             % by weight                                              ______________________________________                                        Polyoxyethylene glycerol sorbitan                                                                    3.600                                                  fatty acid ester (Arlacel 988)                                                Polyoxyethylene fatty acid ester                                                                     1.400                                                  (Arlacel 989)                                                                 Cetearyl Alcohol (Lanette O)                                                                         2.000                                                  Mineral Oil, GP 9      25.000                                                 Paraben mixture        as desired                                             Magnesium sulphate (MgSO.sub.4 * 7 H.sub.2 O)                                                        0.700                                                  UCA                    1.250                                                  Water demin.           to 100.000                                             ______________________________________                                    

EXAMPLE 12

W/O-Lotion

    ______________________________________                                                             % by weight                                              ______________________________________                                        Glycerol sorbitan fatty acid ester                                                                   1.300                                                  (Arlacel 481)                                                                 Polyoxyethylen fatty acid ester                                                                      3.700                                                  (Arlacel 989)                                                                 Neutral Oil (Miglyol)  6.000                                                  Paraffin Oil, GP 9     14.000                                                 Propylene glycol       3.800                                                  Magnesium sulphate (MgSO.sub.4 * 7 H.sub.2 O)                                                        0.700                                                  UCA                    0.060                                                  Water demin.           to 100.000                                             ______________________________________                                    

EXAMPLE 13

O/W-Emulsion

    ______________________________________                                                           % by weight                                                ______________________________________                                        PEG 100 Stearate (Arlacel 165)                                                                     5.000                                                    Cetearyl Alcohol (Lanette O)                                                                       3.000                                                    Mineral Oil, GP 9    25.000                                                   Paraben mixture      as desired                                               UCA                  0.325                                                    Water demin.         to 100.000                                               ______________________________________                                    

EXAMPLE 14

O/W-Emulsion

    ______________________________________                                                          % by weight                                                 ______________________________________                                        Polysorbate-60 (Tween 60)                                                                         3.000                                                     Sorbitan Stearate (Arlacel 60)                                                                    2.000                                                     Cetearyl Alcohol (Lanette 0)                                                                      3.000                                                     Mineral Oil, GP 9   25.000                                                    Paraben mixture     as desired                                                UCA                 0.035                                                     Water demin.        to 100.000                                                ______________________________________                                    

EXAMPLE 15

Cation active Emulsion

    ______________________________________                                                            % by weight                                               ______________________________________                                        Distearyldimethylammonium chloride                                                                  5.000                                                   (Genamin DS AC)                                                               Petroleum jelly, GP 9 5.000                                                   Isopropyl palmitate   2.000                                                   Cetyl alcohol         1.000                                                   Silicone Oil          0.100                                                   Propylparaben         0.100                                                   Methylparaben         0.100                                                   Glycerol              4.000                                                   UCA                   0.090                                                   Water demin.          to 100.000                                              ______________________________________                                    

EXAMPLE 16

Emulsion

    ______________________________________                                                         % by weight                                                  ______________________________________                                        Sodium cetearyl sulphate                                                                         6.000                                                      (Emulgade F)                                                                  Mineral Oil, GP 9  25.000                                                     Paraben mixture    as desired                                                 UCA                0.450                                                      Water demin.       to 100.000                                                 ______________________________________                                    

EXAMPLE 17

O/W-Emulsion

    ______________________________________                                                          % by weight                                                 ______________________________________                                        Stearic acid        5.000                                                     Cetearyl Alcohol (Lanette 0)                                                                      3.000                                                     Mineral Oil, GP 9   25.000                                                    Paraben mixture     as desired                                                Triethanolamine     1.000                                                     UCA                 0.080                                                     Water demin.        to 100.000                                                ______________________________________                                    

Evidence of cis-urocaninic acid induced suppression of contact allergyinduced by DNFB (dinitrofluorobenzene).

Material and Methods

Experiment (1)

Test animals: Ten naive, syngeneic female mice per group (age: 12-14weeks) were used as test animals in the experiments.

Urocaninic acid: trans-Urocaninic acid was purchased from Sigma (Munich,Germany). For isomerisation the trans-uracinic acid solution (1% in ddH₂ O buffered with NaOH to pH 6.9) was irradiated with an Osram Vitaluxlamp (300 W) to get a conversion of 50% of trans-urocaninic acid tocis-Urocaninic acid, controlled by HPLC-analysis.

The solution of cis/trans racemate was passed through a 0.1 μm Milliporefilter and formulated in an O/W cream (1 mg urocaninic acid/ml cream)within the aqueous phase. The O/W-formulation without urocaninic acidserved as control.

Induction and elicitation of contact allergy to DNFB:

DNFB purchased from Sigma (Munich, Germany) was used as allergen toinduce contact allergy (delayed type hypersensitivity (DH) reaction.Before sensibilisation with DNFB 10 mice per group were treated dailyabout a period of 3 days with 100 μl urocaninic acid cream (group A)respectively with 100 μl placebo cream (group B) on shaved abdominalskin areas (6 cm²).

5 hours after the last topical application of cream mice of both groupswere sensitized by epicutaneous treatment on the shaved abdominal skinareas with 30 μl of DNFB (0.6%) soluted in aceton/olive oil (4:1).

8 days later the mice of group A were embrocated on the surface of oneear with 10 μl of urocaninic acid cream (data group A II) and on thesurface of the other ear with 10 μl placebo cream (data group A I).Additionally the mice of group B were embrocated on the surface of oneear with 10 μl of urocaninic acid cream (data group B II) and on theother ear with 10 μl placebo cream (data group B I). The distribution ofthe ears treated with cream (left or right) was statistically randomizedin each animal group.

One day later the thickness of both ears in all groups were measuredwith a micrometer to determine the basic values. Thereafter all micewere challenged with 20 μl DNFB (0.5%) on the surface of both ears and24 hours later ear thickness was remeasured.

The DH response was calculated as the average of increase in earthickness per mouse (net ear swelling). The percentage of DH suppressionwas calculated for ears treated with and without active agent(=cis-urocaninic acid) according to the formula: ##EQU1##

The statistical significance of data was calculated by the WilcoxonU-test.

Results (shown in Tab. 1):

The arithmetical mean values of ear thickness were not statisticallydifferent in both groups of mice before DNFB challenge. However, 24hours after DNFB challenge the ear thickness in data group B I (vis.Tab. 1) was significantly encreased in comparison with the data groups AI and B II.

These data give good evidence that either prophylactic treatment withcis-urocaninic acid containing formulations or, in case ofsensibilization has already occurred, the treatment with cis-urocaninicacid containing formulations before repeated allergen contact giveprotection from DH-reaction.

                  TABLE 1                                                         ______________________________________                                        Effect of O/W-creams formulated with or without                               urocaninic                                                                    acid on DH response against DNFB                                                       on days 1-3 on day 11                                                data     treated with                                                                              treated with                                                                             ear swelling                                  group    (abdomen)   (ear)      day 13                                        ______________________________________                                        A I      active agent                                                                              placebo    7.96 (0.90)                                   A II     active agent                                                                              active agent                                                                             4.95 (0.98)                                   B I      placebo     placebo    11.87 (1.07)                                  B II     placebo     active agent                                                                             7.33 (0.57)                                   ______________________________________                                        active agent = cream containing urocaninic acid =                             Formulation A                                                                 placebo = cream not containing urocaninic acid = Formulation                  Ear swelling was measured in mm * 10.sup.-2. The values in brackets           are standard deviations of the mean values.                                   The ratios of the groups (suppression of ear swelling in %)                   are:                                                                          A I:B I = 32.1%                                                               A II:A I = 37.9%                                                              A II:B I = 58.3%                                                              A II:B II = 32.5%                                                             B II:A I = 8.0%                                                               B II:B I = 38.3%                                                          

Experiment (2)

Test animals: As in Experiment (1)

Urocaninic acid: As in Experiment (1). The solution of cis/transracemate was passed through a 0. 1 μm Millipore filter and formulated inan O/W cream (1 mg urocaninic acid/ml cream) within the aqueous phase.The cream additionally contained 0.75% by weight of gamma-linoleic acid.

The O/W-formulation without urocaninic acid but containinggamma-linoleic acid served as control.

Induction and elicitation of contact allergy to DNFB:

Before sensibilisation with DNFB 10 mice per group were treated dailyabout a period of 3 days with 100 μl urocaninic acid cream (group C)respectively with 100 μl placebo cream (group D) on shaved abdominalskin areas (6 cm²).

5 hours after the last topical application of cream mice of both groupswere sensitized by epicutaneous treatment on the shaved abdominal skinareas with 30 μl of DNFB (0.6%) soluted in aceton/olive oil (4:1).

8 days later the mice of group C were embrocated on the surface of oneear with 10 μl of urocaninic acid cream (data group C II) and on theother ear with 10 μl placebo cream (data group C I). Additionally themice of group D were embrocated on the surface of one ear with 10 μl ofurocaninic acid cream (data group D II) and on the other ear with 10 μlplacebo cream (data group D I). The distribution of the ears treatedwith cream (left or right) was statistically randomized in each animalgroup.

One day later the thickness of both ears in all groups were measuredwith a micrometer to determine the basic values. Thereafter all micewere challenged with 20 μl DNFB (0.5%) on the surface of both ears and24 hours later ear thickness was remeasured.

The DH response was calculated as the average of increase in earthickness per mouse (net ear swelling). The percentage of DH suppressionwas calculated for ears treated with and without active agent accordingto the formula: ##EQU2##

The statistical significance of data was calculated by the WilcoxonU-test.

Results (shown in Tab. 2):

The arithmetical mean values of ear thickness were not statisticallydifferent in both groups of mice before DNFB challenge. However, 24hours after DNFB challenge the ear thickness in data group D I (vis.Tab. 1) was significantly encreased in comparison with the data groups CI and D II.

These data give good evidence that either prophylactic treatment withcis-urocaninic acid containing formulations or, in case of sensitationhas already occurred, the treatment with cis-urocaninic acid containingformulations before repeated allergen contact give protection fromDH-reaction.

                  TABLE 2                                                         ______________________________________                                        Effect of O/W-creams formulated with or without                               urocaninic                                                                    acid on DH response against DNFB                                                       on days 1-3 on day 11                                                data     treated with                                                                              treated with                                                                             ear swelling                                  group    (abdomen)   (ear)      day 13                                        ______________________________________                                        C I      active agent                                                                              placebo    7.74 (0.87)                                   C II     active agent                                                                              active agent                                                                             4.02 (1.02)                                   D I      placebo     placebo    11.70 (1.01)                                  D II     placebo     active agent                                                                             6.99 (0.70)                                   ______________________________________                                        active agent = cream containing urocaninic acid = Formulation                 placebo = cream not containing urocaninic acid =                              Formulation D                                                                 Ear swelling was measured in mm * 10.sup.-2. The values in brackets           are standard deviations of the mean values.                                   The ratios of the groups (suppression of ear swelling in %)                   are:                                                                          A I:B I = 33.8%                                                               A II:A I = 48.1%                                                              A II:B I = 65.6%                                                              A II:B II = 42.5%                                                             B II:A I = 9.7%                                                               B II:B I = 40.3%                                                          

Experiment (3)

Test on antiinflammatory activity:

After UV-irradiation (Sol 3, Honle, Germany) the irradiated skin (areaof the irradiated skin 1.0*1.2 cm²) was treated with the testformulations.

(1) Test formulation A was applied on 14 volunteers (average age: 31,2years, standard deviation 7,6 years) immediately after UV irradiationand a second time 6 hours after irradiation. The cream was weighed, thusthe applied quantity was 2 mg/cm².

(2) Test formulation B was applied on 14 volunteers, immediately afterUV irradiation and a second time 6 hours after irradiation. The creamwas weighed, thus the applied quantity was 2 mg/cm².

(3) Test formulation C was applied on 14 volunteers, immediately afterUV irradiation and a second time 6 hours after irradiation. The creamwas weighed, thus the applied quantity was 2 mg/cm².

(4) Test formulation D was applied on 14 volunteers, immediately afterUV irradiation and a second time 6 hours after irradiation. The creamwas weighed, thus the applied quantity was 2 mg/cm².

Results:

The induced erythemas were evaluated visually, 24 hours afterirradiation:

    ______________________________________                                        (a) 12 persons                                                                              weak erythema,                                                                             2 persons                                                                            distinct erythema                           (b) 13 persons                                                                              distinct erythema,                                                                         1 person                                                                             weak erythema                               (c) 13 persons                                                                              no erythema, 1 person                                                                             weak erythema                               (d) 10 persons                                                                              distinct erythema,                                                                         3 persons                                                                            weak erythema,                                  1 person  severe erythema                                                 ______________________________________                                    

Experiment (4)

An O/W-cream according to formulation E (active agent) was applied overa period of 3 days, once a day, to the left volar forearm of a volunteersuffering from nickel allergy and an O/W-cream according to formulationF (placebo) was applied to his right volar forearm. Immediately afterthe last application both forearms were challenged with 20 μl of a NiSO₄-mixture 0.1% in vaseline. The reactions were evaluated visually 72hours after application of the allergen. Whereas the placebo-treatedforearm showed a distinct allergic reaction, the forearm treated withactive agent revealed only slight erythema.

Experiment (5)

A volunteer suffering from psoriasis was treated twice a day over aperiod of six weeks with

(5.1) a composition according to formulation A in the region of the leftelbow

(5.2) a composition according to formulation B in the region of theright elbow.

Both elbows revealed symptoms of psoriasis before the experiment.

Results:

After six weeks, the symptoms of psoriasis had been reduced on the leftelbow. On the right elbow no change could be noticed.

Experiment (6)

A volunteer suffering from severe psoriasis was treated twice a day overa period of six weeks with

(6.1) a composition according to formulation C in the region of the leftelbow

(6.2) a composition according to formulation D in the region of theright elbow.

Both elbows revealed severe symptoms of psoriasis before the experiment.

Results:

After six weeks, the symptoms of psoriasis had been reduced on the leftelbow. On the right elbow no change could be noticed.

Formulations according to Experiments (1)-(6)

The active agent containing cream A had the formula

    ______________________________________                                        Ceteareth-20       3,00                                                       Cetylstearylalcohol                                                                              8,00                                                       Vaseline          10,00                                                       Mineral Oil       10,00                                                       UCA                1,00                                                       Water demin.      68,00                                                       ______________________________________                                    

The placebo B had the formula

    ______________________________________                                        Ceteareth-20       3,00                                                       Cetylstearylalcohol                                                                              8,00                                                       Vaseline          10,00                                                       Mineral Oil       10,00                                                       Water demin.      69,00                                                       ______________________________________                                    

The active agent containing cream C had the formula

    ______________________________________                                        Ceteareth-20      3,00                                                        Cetylstearylalcohol                                                                             8,00                                                        Vaseline          10,00                                                       Mineral Oil       10,00                                                       UCA               1,00                                                        gamma-linolenic acid                                                                            0,75                                                        Water demin.      67,25                                                       ______________________________________                                    

The placebo D had the formula

    ______________________________________                                        Ceteareth-20      3,00                                                        Cetylstearylalcohol                                                                             8,00                                                        Vaseline          10,00                                                       Mineral Oil       10,00                                                       gamma-linolenic acid                                                                            0,75                                                        Water demin.      68,25                                                       ______________________________________                                    

The active agent containing cream E had the formula

    ______________________________________                                        Ceteareth-20       3,00                                                       Cetylstearylalcohol                                                                              8,00                                                       Vaseline          10,00                                                       Mineral Oil       10,00                                                       UCA                2,00                                                       Water demin.      67,00                                                       ______________________________________                                    

The placebo F had the formula

    ______________________________________                                        Ceteareth-20       3,00                                                       Cetylstearylalcohol                                                                              8,00                                                       Vaseline          10,00                                                       Mineral Oil       10,00                                                       Water demin.      69,00                                                       ______________________________________                                    

We claim:
 1. A method for the treatment of a human patient afflictedwith psoriasis, which comprises topically administering to such patientan amount effective for treating such psoriasis of cis-urocanic acid ora salt thereof.
 2. The method according to claim 1, wherein thecis-urocanic acid or salt thereof is applied as a composition alsocontaining a diluent.
 3. The method according to claim 2, wherein thecomposition contains about 0.0001 mg/ml-60 mg/ml of the cis-urocanicacid or salt thereof.
 4. The method according to claim 2, wherein thecomposition further contains about 0.2-2% by weight of an unsaturatedfatty acid, ester or salt thereof.
 5. The method according to claim 1,wherein the cis-urocanic acid or salt thereof is applied in admixturewith trans-urocanic acid or salt thereof.
 6. The method according toclaim 1, wherein the cis-urocanic acid or salt thereof is applied as aracemic mixture with trans-urocanic acid or a salt thereof.